The faucet center is the distance in inches between pre-drilled faucet holes. Measuring the hole spacing or faucet center ensures you get the correct size faucet (or deck plate) for your mounting area.
For an accurate faucet center, simply measure the distance between the outermost faucet holes. In other words, measure from the centerpoint of the far left hole to the centerpoint of the far right hole. Most faucet centers range between 4 and 16 inches, with widespread faucets typically measuring at 6 to 8 inches and centerset faucets measuring at 4 inches.
If your sink or vanity has only one pre-drilled faucet hole, then you’ll want a single-hole faucet that includes a handle. If you have a 4-inch faucet center but want a single-hole vanity faucet, you can install a escutcheon plate to hide the additional pre-drilled holes.